Cardiovascular Events and Mortality in Patients Undergoing Adjuvant Radiotherapy for Breast Cancer: a Systematic Review

Objective We performed a systematic review to quantify the cardiovascular risk of adjuvant radiotherapy (RT) for breast cancer. Methods A literature search was conducted using MEDLINE, Embase, and the Cochrane Central Register of Controlled Trials from inception to July 2020. Results The literature search produced 7363 reports, of which 76 met our inclusion criteria. In studies comparing left-sided RT with right-sided RT, 7 of 35 (20%) studies found increased cardiovascular mortality, and 8 of 28 (29%) studies found increased cardiovascular events. In studies comparing patients who received RT with those who did not, 7 of 26 (27%) studies found increased cardiovascular mortality, and 5 of 22 (23%) studies found increased cardiovascular events. Conclusion Most of the studies that found significant associations between laterality and cardiovascular risks included treatment periods that started prior to 1985, suggesting that modern RT techniques have minimised the cardiac exposure in breast cancer patients receiving RT. However, more focused studies must be conducted to investigate the long- term cardiovascular risk associated with modern RT techniques.